The present invention generally relates to an apparatus and methods for cleaning contact lenses. More particularly, the invention relates to an apparatus and method by which contact lenses, and specifically those which are water and/or gas permeable, are cleaned by the efficient application of an electrical field focused through the lens. Under the influence of the electrical field, contaminants migrate quickly from above and below the surface of the lens.
Contact lenses are thin films having a dominant convex surface and a dominant concave surface for placement directly onto a wearer's eyes generally to correct defects in vision. Contact lenses may be made from a variety of materials. One widely used type of material from which contact lens may be made is a gas permeable plastic. Another type or material comprises a hydrophilic gel. Both of these types of lenses are, on a molecular level, characteristically water-filled porous lattices that are water and/or ion permeable. Reference will be made herein to these types of lenses as permeable.
While the hydrated porosity of a permeable lens is advantageous in that it generally allows this type of lens to rest on the wearer's cornea without producing irritation, it is disadvantageous from the maintenance perspective. The water-filled porous structure of a permeable lens allows contaminants to become absorbed upon, or trapped below the surface of the lens.
Lens contaminants come from a variety of sources. The wearer's tears are generally the most significant single source of lens contamination. Many different types of inorganic and organic molecules and organisms become selectively absorbed onto a lens from the fluid which constantly bathes the lens. Another source is the atmosphere--a variety of inorganic and organic substances and organisms may be absorbed directly from the atmosphere onto or within the lens. The simple handling of the lens, such as when the lens is being placed on or taken off of the cornea, may cause a variety of contaminants, including oil, dirt, and bacteria or other organisms, to be transferred to the lens.
Contaminants diminish the optical performance of a lens. After a lens has been worn for a period of time, deposits become evident on or within the lens' clear structure. The deposits may appear as a white, partially, opaque occlusion or as a semi-transparent, possibly colored layer. Further problematic is that lens contaminants act as a substrate to facilitate the deposit of other inorganic or organic substances onto or within the lens. Visual acuity decreases with an increase in the lens opacity caused by the deposits.
Besides affecting the optical performance of a lens, lens contaminants can also affect the physiology of the eye. The contaminants act as a source of irritation. Further important to the wearer's health is that lens contaminants provide a suitable environment within which deleterious organisms such as bacteria, fungi, and yeast may flourish. Conjunctivitis or giant papillary conjunctivities may result from the contamination of a lens.
To lengthen the useful life of their contact lenses and avoid the physiological problems associated with contaminated lenses, wearers are instructed to follow a periodic cleaning and sterilizing regime. Because such procedures often include time consuming steps involving the use of often costly chemicals or equipment, wearers are generally lax in following the prescribed procedures and often make only a perfunctory and less than regular attempt at removing contaminants from the surface of their lenses.
Of the known apparatus and methods with which wearers may attempt to clean and/or sterilize their lenses, many include physical-based apparatus and methods, such as those that require scrubbing, agitation, and/or swirling. Other apparatus and methods are chemical-based and may employ surfactants, oxidizing agents, and/or enzymes. However, such conventional cleaning apparatus and methods are generally limited in their ability to clean a permeable lens completely and/or without harm to the lens.
To illustrate, known apparatus and techniques, such as those that clean by scrubbing or that rely on the use of strong chemicals, damage the fragile lattice structure from which permeable lenses are made. Other conventional apparatus and methods, while they may not damage a lens during cleaning, are unable to remove all of the contaminants lodged on the surface and may be wholly unable to remove contaminants situated farther below the surface of the lens. Even after a lens has been superficially cleaned, many conventional apparatus and methods leave a residue consisting of dislodged contaminants, chemicals, or a combination of both on, or below the surface of the lens. This residue may irritate or damage the cornea of the wearer. Also many conventional apparatus and methods require extended handling of the lens. Handling allows dirt and/or oil to be transferred to the lens plus may cause damage to the fragile, soft structure of the lens.
The present invention cleans permeable lens quickly and efficiently and without damage to it. The novel apparatus of this invention includes opposing terminals--with which separate electric charges may be conducted to an inner opening of a receptacle--and transmission media--composed of a substance by which a lens may be aligned between the terminals without damage to the surface or body of the lens and which when wetted is suitable for transmitting electrical charge and thereby focusing an electric current through the lens aligned on a member or members made from the media between the terminals.
In one preferred embodiment of the present invention, members made from the transmission media directly cover, without overlap, the dominant convex surface and the dominant concave surface of a lens so that the lens is aligned without distortion between the terminals. In a second preferred embodiment, the apparatus includes a member made form the transmission media that generally covers the dominant convex surface of the lens and a second member made from the transmission media that extends from one terminal into a layer of fluid covering the dominant concave surface of the lens. In a third embodiment, the apparatus includes one member made from the transmission media that generally covers the dominant convex surface of the lens to hold it in supportive alignment between the terminals, one terminal of which extends into fluid covering the dominant surface of the lens. Depending on the embodiment, the terminals may directly contact the transmission media members, the members being positioned to separately cover the dominant surfaces of the lens. Alternatively, one of the terminals may make indirect contact with one of the members covering one of the len's surface through a body of fluid. Additionally, one of the members may extend from direct contact with one of the terminals to a layer of fluid covering the concave surface of the lens. A different charge formed in each terminal is transmitted from each terminal: through a media member with which the terminal is in direct contact and to the lens; through a media member to a layer of fluid covering the lens concave surface and to the lens; or through a body of fluid to one of the media members in contact with the fluid and to the lens.
Because the media members, or, in other preferred embodiments, the fluid layer and the single media member, do not touch each other, the electrical current cannot "leak" around the lens and must flow through the lens. By focusing the electrical current through the lens, the present invention overcomes the disadvantages of conventional apparatus, such as that disclosed in U.S. Pat. No. 4,732,185, in which the lens is simply immersed in a body of fluid thereby allowing the current to flow--according to the path of least resistance--around the lens. At best, a partially clean lens results from the use of such conventional apparatus. With the present invention, the focused electrical current causes contaminants, such as inorganic and organic substances and organisms, to quickly migrate from below of, and off the surfaces of the lens. The contaminants pulled from the lens may be captured by a transmission media member. Any contaminants which remain loosely on the surfaces of the lens may be washed off. As the media member may be made from disposable material, the health risks associated with the cleaning of contaminated contact lens are lessened. It is through the use of the present invention that a permeable lens is cleaned and sterilized.
It is, accordingly, a general object of the present invention to provide an apparatus and methods by which lenses may be cleaned and sterilized.
Another object of the present invention is to provide an apparatus and methods by which permeable lenses may be cleaned and sterilized through the application of an electrical field.
An additional object of the present invention is to provide an apparatus and methods which utilize separate terminals to establish an electric current through a permeable lens aligned therebetween thereby cleaning the lens.
A further object of the present invention is to provide an apparatus and methods that facilitate the efficient use of an electric current to clean a permeable lens by allowing the electrical current to pass only through the lens to draw contaminants off and from within the body of the lens.
These and other, features and advantages of this invention will be clearly understood and explained with reference to the accompanying drawings and through a consideration of the following detailed description of the preferred embodiments.